MAINTENANCE OF HIGH VIRUS LOAD EVEN AFTER SEROCONVERSION IN NEWBORN CATS ACUTELY INFECTED WITH FELINE IMMUNODEFICIENCY VIRUS

The viral loads in adult and newborn eats have been compared following injection with feline CD4(+) FeL-039 line cells acutely infected with feline immunodeficiency virus (FIV). The level of virus genome in per ipheral blood mononuclear cells (PBMC) increased progressively despite seroconversion in the newborn cats, whereas the virus genome was appa rently cleared after seroconversion in the adult cats. Immunohistochem ical staining of thymus of the FIV-infected newborne cats showed clust ers of viral antigen-positive cells. These results indicate that FIV i nfection of the newborn cat results in higher virus loads than infecti on of the adult cat. We discuss these findings in relation to FIV as a model system for studies of the infection of neonates with an immunos uppressive retrovirus.